Unitary filter cartridge with flow transition mouth

Abstract

A high efficiency unitary cartridge filter for installation with a separate sealing gasket in a generally uniform circular or oblong hole of a baghouse tube sheet. The cartridge includes a plastic or metal tubular core around which is wrapped elongate pleated filter media to form a pleat pack. The pleat pack is sealed at the lower end thereof by a molded cap. A molded upper fitting includes an aerodynamically contoured transition mouth comprising compound radii of curvatures and a bore which closely corresponds to the bore of the tubular core for improved cleaning power and increased pressure during a cleaning cycle and for reduced pressure drop during normal filtering operation. The molded top may optionally incorporate and bond with a metal collar for added structural integrity and may also incorporate electrical grounding elements for grounding a metal core to the baghouse tube sheet.

Having thus described my invention, I claim: 
     
       1. A high efficiency, unitary filter cartridge to be removably, but sealingly installed with a separate sealing gasket, in a uniform hole of the tube sheet for a pulse-jet baghouse, said filter cartridge comprising:
 an elongate, perforated support conduit having a uniform internal bore and further having first and second ends; 
 a pleated filter sleeve geometrically circumscribing said support conduit and having first and second ends; 
 a bottom end cap secured to said second ends of said support conduit and filter sleeve to sealingly close said second ends; 
 a molded, open mouth top fitting secured to said first ends of said support conduit and filter sleeve, said top fitting having an upper flange configured and sized such that a portion of said flange overlies the tube sheet adjacent said hole therein, said top fitting having a side wall integrally formed with said upper flange to extend downwardly therefrom and being configured and sized to fit through said hole of the tube sheet in which said filter cartridge is installed, said top fitting having an interiorly flared open mouth with a rounded shoulder integrally formed with said upper flange and transitioning to a throat portion with a bore configured and sized to substantially correspond to said bore of said support conduit, wherein said rounded shoulder is continuously curved from said upper flange to said throat portion; 
 whereby, when said filter cartridge is installed in said hole of said tube sheet, said top fitting biases said sealing gasket to engagement with said tube sheet to create a leak proof seal between said top fitting and said tube sheet. 
 
     
     
       2. The filter cartridge as in  claim 1  wherein said rounded shoulder of said filter mouth is formed as a smoothly contoured surface with compound radii of curvatures from a horizontal plane defining the opening of said mouth to the bore of said throat. 
     
     
       3. The filter cartridge as in  claim 1  wherein said perforated support conduit is formed of foraminous plastic. 
     
     
       4. The filter cartridge as in  claim 1  wherein said perforated support conduit is formed of foraminous metal. 
     
     
       5. The filter cartridge as in  claim 4  including an electrical grounding wire connected to said support conduit and threaded through said top fitting to be exteriorly accessible for grounding to a suitable electrical ground of the baghouse. 
     
     
       6. The filter cartridge as in  claim 1  said top fitting including a metal collar bonded to said top fitting for increased structural integrity, said metal collar having a flange configured and sized such that at least a portion thereof overlies the tube sheet adjacent said hole in which said filter cartridge is installed in order to compress said sealing gasket between said flange and said tube sheet, and said metal collar having a cuff portion contiguous with said flange and extending downwardly therefrom wherein said cuff is configured and sized smaller than said hole in the tube sheet in order to penetrate said hole when said filter cartridge is installed on the tube sheet. 
     
     
       7. The filter cartridge as in  claim 6  said flange of said metal collar shaped as an inverted cup to contain said sealing gasket thereunder and said cuff portion contiguous with said flange and extending downwardly therefrom around the molding material of said top fitting to be received within said hole in the tube sheet. 
     
     
       8. The filter cartridge as in  claim 6  wherein the outermost portion of said flange of said metal collar is shaped as an inverted cup to contain said sealing gasket thereunder and the innermost portion of said flange and said cuff portion is embedded within the molding material of said top fitting. 
     
     
       9. The filter cartridge as in  claim 8  wherein the outermost portion of said flange of said metal collar is shaped as an inverted cup to contain said sealing gasket thereunder and the innermost portion of said flange and said cuff portion is embedded within the molding material of said top fitting, and said cuff portion extends downwardly a distance sufficient to contact the pleated filter sleeve and thereby support said sleeve and conduit during the molding process. 
     
     
       10. The filter cartridge as in  claim 6  wherein said support conduit is fabricated of metal and said filter further includes an electrical grounding wire connected to said support conduit and threaded through said top fitting to be exteriorly accessible for grounding to a suitable electrical ground of the baghouse. 
     
     
       11. The filter cartridge as in  claim 6  wherein said support conduit is fabricated of metal and said filter further includes an electrical spring clip secured to said support conduit and embedded within said top fitting to engage said metal collar for grounding to said tube sheet of the baghouse. 
     
     
       12. The filter cartridge as in  claim 6  configured and sized in cross-section as an oblong shape. 
     
     
       13. The filter cartridge as in  claim 12  configured and sized in cross-section such that said bore of said throat is formed with semicircular ends, each end having the same diameter, and with spaced apart parallel sides emanating from said semicircular ends. 
     
     
       14. The filter cartridge as in  claim 12  having a width and length configured and sized in cross-section such that said bore of said throat is formed with semicircular ends, each end having the same diameter, and with spaced apart parallel sides emanating from said semicircular ends wherein the cross-sectional area satisfies the relationship A=WL−0.2146W 2 . 
     
     
       15. The filter cartridge as in  claim 1  configured and sized in cross-section as a circular shape. 
     
     
       16. The filter cartridge as in  claim 15  wherein the bore of said mouth includes a lateral distance D across said bore and said rounded shoulder of said filter mouth is smoothly contoured such that a first radius of curvature R 1  equal to 0.2D centered at a point located a distance of 0.75D from the longitudinal centerline of said lateral distance D and a distance of 0.2D down from said horizontal plane defining the opening of said mouth extends from said horizontal plane down to a second radius of curvature R 2  equal to D/3 centered at a point located a distance of 0.833D from the longitudinal centerline of said lateral distance D and a distance of 0.304D 0.2D down from said horizontal plane defining the opening of said mouth. 
     
     
       17. The filter cartridge as in  claim 15 , said top fitting including a spiral thread on the exterior surface of said side wall in order for an external torsional force to assist in installation and removal of the filter cartridge from the tube sheet of the baghouse. 
     
     
       18. The filter cartridge as in  claim 15 , said top fitting including an outwardly projecting circumferential ridge on the exterior surface of said side wall in order engage a portion of said sealing gasket and to prevent said filter cartridge from working loose from its installed condition on the tube sheet of the baghouse.